CD81 APC

CD81, also known as Target of the Antiproliferative Antibody 1 (TAPA-1) or Tetraspanin-28 (TSPAN28), is a 26 kDa transmembrane protein belonging to the tetraspanin (TM4SF) family. It plays a role in cell growth, signal transduction, and immune cell interactions. CD81 is widely expressed across various cell types, including hematopoietic, neuroectodermal, and mesenchymal cells. Within the immune system, it is found on B and T lymphocytes, NK cells, thymocytes, eosinophils, monocytes, dendritic cells, and endothelial cells, while being absent from neutrophils, platelets, and erythrocytes. Functionally, CD81 is involved in B cell adhesion through VLA-4 integrin and contributes to early T cell development. It forms a multimolecular complex with other cell-surface proteins, including CD19, CD21, CD20, CD37, CD53, and CD82 in B cells, as well as CD4, CD8, and CD82 in T cells. Studies indicate that CD81-specific antibodies can exert antiproliferative effects on lymphoid cell lines, particularly large cell lymphomas, and promote homotypic cell aggregation. Additionally, CD81 interacts with CD19, CD21, and CD225, playing a key role in B cell activation and growth regulation. Anti-CD81 (CBI.164) is a recombinant antibody.